It is a common practice, where an electric cable or fluid hose has to pass through a hole in a metal panel, to provide in the hole a plastics bushing which is arranged to grip the cable or hose firmly so that tension applied to the cable or hose at one side of the panel will not be transmitted to the other. It is also known to make the hole in the panel other than round, and for the bushing to have a complementary external cross-section so that torque applied to the cable or hose at one side of the panel will likewise not be transmitted to the other.
A strain relief bushing is known which can be inserted in a non-circular hole in a panel to permit a cable or hose to be threaded through it and the cable or hose then gripped by a ratchet-like tooth hinged in an aperture at one side of the bushing and bearing on a flexible finger which is caused to press against and grip the cable or hose. A shortcoming of this arrangement is that the grip of the bushing on the cable or hose cannot be released as readily as may be desirable.